The revival of this claim by the elector provoked an invasion of the mark by an army of Pomeranians with their allies in 1420, when Frederick inflicted a severe defeat upon them at Angermiinde; but in 1424 a temporary coolness between the elector and the emperor Sigismund led to a renewal of the attack which Frederick was unable to repulse.
Albert appeared in Brandenburg early in the same year, and after receiving the homage of his people took up the struggle with the Pomeranians, which he soon brought to a satisfactory conclusion; for in May 1472 he not only obtained the cession of several districts, but was recognized as the suzerain of Pomerania and as its future ruler.
The Pomeranians, inspired by the declaration of the emperor Frederick III.
To deal with these difficulties Albert returned to Brandenburg in 1478, and during his stay drove back the Pomeranians, and added Crossen and other parts of duke Henry's possessions to the electorate.
The struggle began in 1109, when Boleslaus inflicted a terrible defeat on the Pomeranians at Nackel which compelled their temporary submission.